KR101651227B1 - Method Of Surface Modifing UHMWPE Fiber Using Oxident Agent - Google Patents

Abstract

The present invention relates to a method for modifying the surface of an UHMWPE fiber, a high-performance fiber, by surface treatment to increase adhesive strength thereof in case of coating with a waterborne polyurethane resin. Microcraters are formed on the surface of the fiber by surface modification of the present invention, and thereby: an adhesive area become wider when a matrix and the fiber bond with each other so the adhesive strength increases; and the interfacial shear stress (IFSS or ILSS) between the matrix and the fiber increases as a bumpy effect so the adhesive strength between the same and the resin increases.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of modifying a surface of a UHMWPE fiber by an oxidizing agent treatment,

The present invention relates to a surface modification method for increasing the adhesive strength of a water-dispersed polyurethane resin by coating the UHMWPE fiber having high strength fiber.

As the safety of the workers in the industrial field becomes more important, the stabilized equipments for the workers have been spreading along with the automation equipment in the developed countries for a long time. However, it is an indispensable factor for operators who are in charge of operating or technical parts of a well-equipped automation facility. Accordingly, the safety equipment to protect the workers has been developed mainly with the upgrading and functionalization, and the market scale is also expanding. As a result, the use amount of a special-coated work glove is increasing to impart breathability to a knitted product using a high-strength yarn satisfying stability and workability at the same time.

Various kinds of coated gloves have been developed continuously since the 1970s with the development of heavy chemical industry as a means to protect workers' hands from external working environment to date. However, due to environmental problems, the development of high-tech industries such as semiconductors, and various industrialization, various requirements that are difficult to meet with existing natural and synthetic rubber or PVC or wet polyurethane gloves have been derived, The development of materials has become necessary.

Currently, gloves are dominated by natural and synthetic rubber, poly (vinyl chloride) (PVC), and wet polyurethane gloves. In the case of natural or synthetic rubber or PVC gloves, durability is decreased due to lack of adhesiveness, thick coating of coating liquid or penetration into the inside of gloves causes direct contact with the human body, which causes discomfort to the wearer and increases fatigue , There arises a problem that the vulcanizing agent and other substances cause environmental pollution in the high temperature production process.

Particularly in the case of PVC gloves, the toxicity of vinyl chloride monomers leads to the release of workers' health hazards and the corrosion of metals due to the release of hydrochloric acid due to heat or light. Particularly, the most serious part is PVC- Dioxins are known to be fatal to the human body due to environmental problems caused by the exposure of dioxins to incineration. In addition, the additives used to impart heat and light stability to PVC are also compounds that contain heavy metals, which have a serious effect on the human body and are regulated. Plasticizers used for imparting processability and flexibility of PVC are also considered to be environmentally harmful substances. Among the most commonly used plasticizers, dioctyl phthalate (DOP), diisononyl phthalate (DINP), butyl benzyl phthalate The phthalate-based plasticizer, etc., enters into the body of a person or an organism and inhibits the normal action of the hormone involved in growth, reproduction, etc., resulting in a decrease in the number of spermatozoa, conversion of male and female, The controversy continues, and the use thereof is limited for some applications.

In the case of natural and synthetic rubber, which is widely used in the glove market, the physical properties of the unvulcanized rubber itself is poor, and the vulcanization (vulcanization) work is required to complete the glove which can be used in the light industry and heavy industry. There is a problem that metal corrosion occurs due to sulfur components and the like.

In the case of wet polyurethane gloves, it is advantageous to wear comfort due to the softness of the microporous type. However, due to excessive sweat discharge due to long-term use, the additive migrates to the surface or absorbs moisture due to the porous structure. Organic solvents and oils penetrate into the gloves easily and come into contact with the hands of the workers. As a result, there is a restriction in use in the high-tech parts industry which is very susceptible to contamination. In addition, due to the nature of wet polyurethane processing, the use of DMF (N, N-Dimethylformamide), an organic solvent, has problems that organic solvents are diffused in wastewater and in the atmosphere.

Therefore, the development of highly functional water-dispersed polyurethane glove material has the effect of solving the disadvantages and defects of these gloves which are mainly used today, that is, the effect of reducing the fatigue of the worker as much as possible and the worker is using the gloves safely It is possible to minimize the pollutants generated during the manufacturing process as well as to minimize the pollutants generated during the manufacturing process and to prevent the pollutants from being discharged to the atmosphere during the manufacturing process of the gloves, It is possible to reduce the use of additives such as various plasticizers and vulcanizers that are environmentally friendly gloves and materials having flexibility such as PVC and synthetic rubber, so that they can be used for semiconductor lead frames and LCD panels. have. In addition, it can be applied to high-tech industrial fields such as semiconductor industry where high-functionality is given and existing gloves could not be used, and it is an opportunity to pioneer overseas export market with high value-added products and to gain import substitution effect.

On the other hand, industrial protective gloves are widely used in industrial fields for safety of workers, maintenance of product quality and improvement of work efficiency. For this purpose, protective gloves consist of two main parts in terms of manufacturing process or product structure. It is a protective film that provides protection against exposure of dangerous external working environment such as liner, substrate, which forms a frame of gloves, and heat or medicine (depending on the application, .

In this case, the material and structure of each part determine various performance as a protective glove. The outer protective layer is a coating of a polymer resin by coating, which contributes to prevention of drug penetration and gripping power of the object being handled , The inner liner is mostly a seamless jersey, which plays a role as a supporter of the polymeric film and has a decisive influence on the protection performance against physical injury caused by external forces such as lips, scratches and stings.

On the other hand, when the resin is applied, most of the resin is hardened after penetrating to a part of the knitted fabric. Thus, the portion where the resin is infiltrated is closely related to the adhesion (durability) of the film and the wearing comfort of the glove. Therefore, in order to manufacture industrial protective gloves with required protection performance and pleasant and flexible fit, it is required to establish the design and manufacturing technology of endothelium and coating resin. Especially, it is required to develop new products that protect the body from physical harmful factors, Is required.

Currently, high-strength yarns have been widely used, but no technology has been developed for knitting or knitting for industrial protective gloves. UHMWPE (High Molecular Weight Polyethylene / UHMWPE) fiber, which is a representative fiber of high tenacity yarn, is also called high strength polyethylene (HSPE) or the like and is a highly oriented polyethylene fiber.

Ultrahigh strength polyethylene has a density of less than 1.0 g / cm ³ (0.97 g / cm ³ ), so it is very lightweight and can float in water without particularly absorbing water. In addition, the high-strength type has a high strength of about 4.0 GPa, which makes it ideal for moving ropes, ropes for coastal mooring of vessels, and sails for yachts. In addition, the excellent transmission of waves such as sound waves, so that when the meat is hooked on the fishing line, the feel of the fishing line becomes good, and it is used as a fishing line and has received a great popularity. Due to its unchanging length in the water, it has recently been used in high-tech fishing gear using fish finders, and has demonstrated high performance in accurately lowering fishing lines to a far distance where fishermen are found.

It is a flexible polymer but has high strength and elongation around 4%, which makes it easy to work in post-processing such as weaving and making. It is also suitable as a protective material, impact resistant material or reinforcing material because it has good balance of high strength and elongation and excellent impact resistance (optical fiber cable reinforcing material, composite material for aerospace, vehicle bulletproof material, bullet proof vest, , Helmets, electric cords, etc.).

The UHMWPE fiber is composed of a monomeric unit of - (CH ₂ -CH ₂ ) -, so its chemical activity is very small and stable. On the other hand, when used as a reinforcing material for a composite material or the like, it exhibits a very weak adhesion to a matrix or a resin. The weak interfacial adhesion force weakens the strength of the composite material due to separation of the interface between the resin and the fibers even at a weak force. Thus, various methods of surface modification are performed in order to exhibit an effective capability as a reinforcing material of a composite material.

This effort is also the case when UHMWPE fiber is used as a high performance protective glove. Interfacial adhesion between the fiber and the coating material is a very important factor when coating the coating material to improve the work performance and safety of the operator. Even if the protective glove is a one-time product, it can not be neglected to remove the coating material in order to increase the reliability of the work.

Generally, there is a method that roughly makes the surface of the fabric roughened by sandpaper or the like, but the strength of the fiber material is weakened and uneven treatment is a problem. In addition, there is a method of irradiating low temperature plasma, but it is mainly batch type, and it is disadvantageous in that it is necessary to make vacuum in the early stage and equipment is expensive. On the other hand, the method of UV irradiation does not need to maintain a vacuum, it can be processed continuously, not batchwise, and it can be said to be more efficient because it requires only an ultraviolet lamp. However, there is a disadvantage that the ultraviolet irradiation time is relatively long in order to obtain the effect to be obtained.

As a countermeasure against this, the adhesive force between the yarn and the polyurethane resin must be strengthened through a separate surface treatment, and various methods have been studied physically and chemically. The simplest method is to rub the surface with sandpaper to increase the surface roughness or to use the flame, but this method is considered to be a method that does not fit well with high strength yarn because it damages the yarn greatly. The chemical modification method is used to etch the surface in a strong acid or a strong base. The physical methods include a low temperature plasma surface treatment method and an ultraviolet ray treatment method which have been recently tried.

As a treatment effect, the method of low temperature plasma is most effective among the physical methods, but it is not easy to apply to materials having a shape and a high price of the equipment to be treated in a vacuum. In recent years, ultraviolet ray irradiation treatment has been studied in a manner that can be applied to materials having low cost and shape and does not require a vacuum. However, the ultraviolet ray treatment is disadvantageous in that the treatment effect is weaker than plasma treatment, A method of treating under an active gas such as ozone is being studied.

Korean Patent Publication No. 1999-0084487 (published on December 06, 1999)

Therefore, it is a technical object of the present invention to provide an oxidant-treated surface modification method for improving the adhesion of water-soluble urethane to a UHMWPE fiber product which can be used as industrial protective gloves and the like.

Therefore, according to the present invention, the UHMWPE fiber product is washed with n-haxane to remove impurities, washed with water and dried in water, immersed in an etching solution consisting of an oxidant aqueous solution for 30 minutes to 8 hours, A method for surface modification of UHMWPE fibers by oxidizing treatment is provided, which comprises washing with water, washing with water in an ultrasonic bath, and then drying.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a surface modification method of increasing the adhesive strength of a water-dispersed polyurethane resin by surface-treating UHMWPE fiber as a high-strength fiber. In order to increase adhesion to a resin, a surface modification method .

UHMWPE fiber is composed of a monomeric unit of - (CH ₂ --CH ₂ ) -, so its chemical activity is very small. When it is used as a reinforcing material for composites for reasons of stability, it shows very weak adhesion to matrix or resin. The weak interfacial adhesion force deteriorates the strength of the composite material because the interface between the resin and the fiber is weakened even at a weak force, so that the present invention provides a surface modification method for exhibiting an effective ability as a reinforcing material of a composite material.

UHMWPE fibers have a smooth surface and do not have a functional group in the main chain. This makes the smooth surface physically roughen to increase the actual contact area between the resin and the fiber, or to increase the chemical adhesion with the resin by varying the chemical composition of the fiber surface. The surface modification method of the present invention relates to a method of immersing in strong acid or alkali to change the etching and chemical composition of the surface.

First, the UHMWPE fiber product was washed with n-haxane to remove impurities, washed with water and dried in water, immersed in an etching solution consisting of an oxidizing agent solution for 30 minutes to 8 hours, subjected to primary washing with ethanol, After a second wash with a bath, it is dried. The oxidant aqueous solution is prepared by mixing an oxidant aqueous solution containing 0.2 to 0.5 molar KMnO ₄ and 0.2 to 0.5 molar HNO ₃ aqueous solution in a volume ratio of 3: 1 to 5: 1, or an aqueous H ₂ O ₂ solution peroxide, Aldrich 50 wt% solution). If the concentration is less than 0.2 mol, there is a problem that the UHMWPE surface modification is insignificant. If the concentration is more than 0.5 mol, the strength of the UHMWPE yarn is greatly deteriorated. In order to oxidize and etch the surface of the UHMWPE without reactive functional groups, an oxidizing agent is required. The time unit for immersing the specimen in the oxidizing agent is 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 8 hours . Each specimen is taken out, washed first with ethanol, and secondly with an ultrasonic bath, and dried thoroughly at about 50 ° C in a dryer.

This surface modification increases the adhesion between UHMWPE fiber and water-dispersed polyurethane resin coated on the surface of UHMWPE fiber. In order to increase adhesion to resin, microcrater is generated on the surface of fiber. These microcritters increase the adhesive strength by increasing the adhesive area when bonding the matrix to the fibers and increase the interfacial shear stress (IFSS or ILSS) between the matrix and the fiber as the unevenness effect.

Therefore, microcrators are generated on the surface of the fiber by the surface modification according to the present invention, thereby increasing the adhesive strength when the matrix and the fiber are adhered to each other to increase the adhesive force. As the unevenness effect, the interface shear stress (IFSS or ILSS) The effect of increasing the adhesion with the resin can be obtained. It is possible to obtain an effect of increasing the dyeing and post-processability due to the surface microcritcher.

1 is an SEM photograph of the surface of the fiber of Example 1 after the surface modification step of the present invention,
2 is an SEM photograph of the surface of the untreated fiber of Comparative Example 1,
FIG. 3 shows AFM images and analysis results of the UHMWPE fibers according to the KMnO ₄ & HNO ₃ solution treatment time of the present invention,
Figure 4 is an AFM image of untreated UHMWPE fiber,
5 is a graph showing the interfacial adhesion between the UHMWPE fiber and the water-dispersed polyurethane resin according to the surface treatment of Example 1,
6 is an SEM photograph of the water-dispersed PU coated fabric of Example 1. Fig.

The following examples illustrate non-limiting examples of methods for modifying the surface of UHMWPE fibers by the oxidant treatment of the present invention.

[Example 1]

The UHMWPE fiber was a Dyneema SK65 from DSM and a plain weave fabric (slope: 18.5, weft: 19) with 1,500 denier filament yarn was used. The n-haxane was washed with a soxhelt device for 24 hours in order to remove the emulsion on the surface of the fabric and the emulsions on the surface of the fabric to remove impurities. It was then washed with distilled water and sufficiently dried at a temperature of 50 캜 in a dryer. First, an aqueous solution of 0.2 molar concentration of KMnO ₄ was prepared and an aqueous solution of HNO ₃ of 0.2 molar concentration was prepared. The prepared KMnO ₄ and HNO ₃ aqueous solutions were mixed at a volume ratio of 4: 1 to prepare an etching solution. The time unit for immersing the specimen in the oxidant was 30 minutes. Each specimen was taken out, washed with ethanol first, washed with an ultrasonic bath, and sufficiently dried at about 50 ° C in a dryer.

As a matrix for the pull-out test, a water-dispersed polyurethane (FG3600) manufactured by TNL Co., Ltd. was used. The prepolymer process, in which the NCO-terminated PU prepolymer with hydrophilic groups was subjected to chain extension after water dispersion, was selected. After thoroughly removing the moisture of the raw materials before the reaction, the raw materials are put into a flask filled with N ₂ gas and stirred. Isocyanate is firstly added and then the selected polyol, anionic ionomer (DMPA, DMBA, sulfonate derivative) Respectively. The temperature in the reactor is maintained at about 75 - 80 캜 and the catalyst is introduced. When the NCO / OH ratio reaches 1.4 to 2.0, the reaction temperature is lowered to about 50 ° C., TEA is added, stirring is continued for 20 minutes, dispersion is started at 50 ° C. or lower, And the reaction is terminated by chain extension.

Gloves or the like knitted with the surface modified UHMWPE fiber were inserted into the glove mold, the coagulant was immersed in the glove mold, then impregnated with the resin mixture solution of the following Table 1 containing the water-dispersed polyurethane resin and dried by hot air at about 100 to 150 ° C Coating gloves were completed.

Resin coating solution Binder Viscosity
(Cps / 25 DEG C) TS
(Kgf / cm ² ) 100% MD
(Kgf / cm ² ) Elongation
(%) Formulation S NBR 2,150 233 20 700

[Example 2]

The treatment was carried out in the same manner as in Example 1 except that the treatment time was 60 minutes.

[Example 3]

The treatment was carried out in the same manner as in Example 1, except that the treatment time was 120 minutes.

[Comparative Example 1]

KMnO ₄ , HNO ₃ aqueous solution and H ₂ O ₂ aqueous solution were not treated in the same manner as in Example 1.

The properties of the surface-treated fabrics and the coated fabrics of the above Examples and Comparative Examples were tested as follows.

end. AFM analysis

AFM is a probe made of stable metal such as tungsten. It is used to grasp the surface morphology of UHMWPE fiber modified by oxidant treatment like SEM. Figure 2 is an SEM image of untreated UHMWPE fiber. In order to investigate the degree of surface change by oxidizing agent treatment, the UHMWPE fabric was treated for 30 minutes and 60 minutes and 120 minutes, and the surface change due to the KMnO ₄ & HNO ₃ solution treatment time was shown together with the analysis results in FIG. In order to confirm the etching type by the strong oxidizing agent, it was immersed in the etching solution for 2 hours and washed with water and observed at 10,000 times and 30,000 times. As shown in the figure, the formation of the microcritor by the strong oxidizing agent is different from that of the UV treatment, and both of the solutions generate a huge microcritter.

All. Pull-out test method of UHMWPE / polyurethane resin

The pull-out test is a direct method of assessing the interfacial adhesion between resin and fiber. In this test, one filament was taken from the fabric woven with the UHMWPE fiber treated in the above, and the resin was a water-dispersed polyurethane (FG 3600) supplied by TNL. For this test, a tongue used in a tensile testing machine was made and used. Ten specimens were used. The fibers were considered to have a circular cross section and their diameters were measured at 20 μm by SEM photographs. The size of the droplet was measured using an optical microscope.

------ Equation (a)

Equation (a) is introduced to obtain the interface shear stress (IFSS). W _max is the load at which the resin and the fiber are separated, S is the area where the fiber and the resin adhere, D is the diameter of the fiber, and L _m is the length of the fiber embedded in the resin.

The specimens were firstly filaments taken from the fabric. The collected filaments were fixed as shown in Fig. When the filaments are fixed, they are processed according to the resin adhesion sequence.

First, the coagulant is applied to the fiber surface, followed by drying, followed by drying at a temperature of 105 ° C. for about 5 minutes. Thereafter, the water-dispersed polyurethane resin was dropped in a water droplet form and fixed and dried. The water-dispersed polyurethane resin fixed on the filament is shown in Fig. The specimens thus obtained are each subjected to labeling, and the length of the fiber in the droplet is measured with a microscope. And since the filaments may cause slip in the jaw of the tensile tester, the ends of the filaments are adhered to the rigid film and the film is measured by jawing.

Prepared specimens were measured using a tensile tester (INSTRON 4467). Self-made tongue was used for tensile testing machine. During the test, the cross-head speed of the tensile testing machine was fixed at 1 mm / min and the values obtained were averaged. FIG. 5 is a graph showing changes in interfacial adhesion between UHMWPE fibers and water-dispersed polyurethane resins according to the surface treatment of Example 1. FIG. The interfacial adhesive strength was not increased more than 90 minutes and the interfacial adhesion was decreased by excessive treatment. It was found that the effect of interfacial adhesion was more significant in KM _n O ₄ & HNO ₃ treatment.

Claims (3)

The UHMWPE fiber product was washed with n-haxane to remove impurities, washed with water, dried and immersed in an etching solution consisting of an oxidizing agent solution for 30 minutes to 8 hours, washed with ethanol firstly, A second washing step, followed by drying. The method for modifying the surface of a UHMWPE fiber by an oxidizing agent treatment. The method according to claim 1,
Wherein the oxidant aqueous solution is an oxidant aqueous solution obtained by mixing KMnO _{4 at a} concentration of 0.2 to 0.5 mol and HNO ₃ aqueous solution at a concentration of 0.2 to 0.5 mol in a volume ratio of 3: 1 to 5: 1, wherein the surface modification of the UHMWPE fiber Way. The method according to claim 1,
Wherein the oxidant aqueous solution is a H ₂ O ₂ aqueous solution (Hydro peroxide, Aldrich 50 wt% solution) at a concentration of 0.2 to 0.5 mol.

Images